文档介绍：摘要 i
摘要
以钾和锰改性的铁基催化剂为研究对象,研究了不同体系中各催化剂的
物理化学性质和它们在 CO 加氢制取低碳烯烃反应中的催化性能。
论文首先分别以氨水沉淀法,溶胶-凝胶法和浸渍法制备了一系列的未
改性的纯 Fe 催化剂,考察了在制备条件,预处理条件和反应条件改变的情况
下,各种催化剂反应性能的变化情况。
溶胶-凝胶法制备的 K/Fe 复合氧化物催化剂 在 300℃, MPa
-1
(H2/CO = 2, V/V),1000 h 的反应条件下具有很高的 C2~C4 低碳烯烃选择性
( wt.%)。而通过共沉淀法得到的具有纳米尺寸(约 20 nm)的 Mn/Fe
-1
(nMn/nFe = 4/96)催化剂在 350℃, MPa (H2/CO = 2, V/V), 1000 h 的反应
条件下也具有很高的低碳烯烃选择性( wt.%)。
钾助剂和锰助剂在对 Fe 进行修饰时,各组分之间在 Si-2 上的引入顺序
会对 CO 加氢性能产生很大的影响,评价反应的结果显示,助剂金属先于 Fe
浸渍到 Si-2 上对提高反应的活性和选择性更有利。
在对比溶胶-凝胶法和氨水共沉淀法制备的 Mn/Fe 催化剂时,我们发现
在传统的“竞争机理”基础上还需要考虑氧物种的演化,才能较合理地解释
以上两种催化剂在反应中的不同性能,因而,论文提出了一个改进型表面竞
争模型。
关键词:合成气,低碳烯烃,铁基催化剂,助剂
ii Abstract
Abstract
Chong Wang (Industrial Catalysis)
Directed by Prof. Qingxia Wang and Prof. Longya Xu
Iron based catalysts modified by potassium and manganese oxides were
investigated on their physicochemical discrepancies and catalytic performances in
CO hydrogenation.
Unmodified iron catalysts were prepared with the method of precipitation,
sol-gel and impregnation. The performances of the catalysts at various reaction
conditions were studied.
K/pound oxide catalysts were prepared by sol-gel technique. In the
CO hydrogenation test under reaction conditions of 300 °C, MPa syngas
-1 = =
(H2/CO = 2, V/V),1000 h , wt.% C2 ~ C4 were given on sample .
Additionally, Mn/Fe catalysts prepared by coprecipitation were in the nano scale
of ca. 20 nm, and the sample of Mn/Fe (nMn/nFe = 4/96) gave high light alkenes
yield of wt.% under the conditions of 350 °C, MPa(H2/CO = 2, V/V),
1000 h-1.
For the impregnated catalysts of K/Mn/Fe/Si-2, it was found that the
impregnating sequence among K, Mn and Fe has great impact on the catalytic
activity and selectivity in CO hydrogenation. Experimental results showed that
impregnating KNO3 prior to Fe(NO3)3 on Si-2 facilitates the improvement of
catalytic selectivity to light alkenes.
In this paper,